Pneumatic tired wheels are widely used in virtually all types of land vehicles, including automobiles, trucks, trailers, tractors, and other self propelled and unpowered vehicles, and aircraft landing gear. The intense development activities involving pneumatic tired wheels and tires has resulted in a highly developed state of the art with respect to tire design, composition, function and reliability.
The performance of pneumatic or gas charged tires is substantially degraded by the loss of inflation pressure. Various attempts have been made to eliminate loss of charge pressure due to tire wall puncture and provide tire designs that will enable the tire to continue to operate in a deflated or “run-flat” condition ranging from modification of tire design to introduction of materials and devices within the tire cavity to support the tire during a deflation period.
These efforts have only been partially successful and often result in limited mobility and loss of steering control and traction, serving to provide mobility for relatively short distances with further destruction of the damaged tire. Further advantages sought for these run-flat adaptations are to provide a replacement for the spare tire and eliminate the need for “on road” changing of the tire. Accordingly, efforts have been directed towards providing vehicle wheels with “run-flat” support devices that better provide vehicle stability and mobility for longer duration and quality of function.
A variety of devices have been developed that may be installed on a pneumatic tired wheel within the tire pressure cavity to support the tire when it is partially or completely deflated without substantially reducing the wheel's effective diameter so that the vehicle stability and control is not compromised. Some of these devices include single and multi-part cushion members that are disposed on the wheel rim between the tire-bead flanges and extend radially outward from wheel axis of rotation to support the tire in a deflated condition. Some of these conventional devices have been fabricated of resilient elastomeric materials of relatively complex construction and may be stretched over the wheel rim to mount on unitary or multi-part rims.
Such devices, if stiff enough to support a tire under run-flat conditions, are difficult to mount on split wheel rims due to the difference in diameter between the tire bead flanges and the interconnecting rim center portion or web. On the other hand, if these devices are resilient enough to be slipped over the bead flanges and engaged with the wheel rim in a static condition, they tend to slip and lose their support position during high speed operation due to centrifugal forces acting thereon.
Some run-flat devices have been equipped with clamps to achieve position maintenance but suffer the difficulty of placement and replacement due to the necessary tight fit against the wheel. Others have been provided with projections on the inner surface of the support structure to maintain wheel contact. These also may be displaced during motion and or involve difficult mounting procedures due to the need to stretch over the wheel rim.
Other multi-component structural inserts have been bolted directly to the wheel via bolts, requiring additional bolt holes drilled into the wheel flange, potentially compromising wheel strength and integrity. The use of multi-component insert structures lessens the difficulty of introduction and/or removal of the structures into the wheel/tire cavity. However, use of “through the wheel” bolt anchors limits the number of bolts that can be anchored in the greater diameter insert structural material resulting in high load strain on the bolts within the structural insert member. Accordingly, further improvements in the field of run-flat support systems are required.